Workshop 2 Hypotheses and Predictions The US cotton industry is dealing with inc

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Workshop 2 Hypotheses and Predictions The US cotton industry is dealing with increased competition from foreign cotton markets. To remain competitive in this textile on a world-wide basis, US cotton growers need to find ways to increase crop yield (the weight of cotton produced per acre- both fiber number and fiber weight) and crop quality (increases in fiber length, wall thickness). 20 30 40 Age (DPA) Figure 1: Increases in fiber length over time in several Figure 2: Changes in fiber number per ovule in several The Observations from the literature . IAA and GA are hormones common to all plants . IAA functions to increase cell division, increase the development of specialized cells . GA functions primarily to enhance cell growth (expansion) . Cotton ovaries exhibit an increase in IAA levels coincides with the timing of fiber initiation, then IAA levels drop, only to increase after 4 DPA In cotton ovules, GA levels rise at about 8 DPA (elongation phase) An analysis of fiber growth (Figure 1) indicates that several different cotton varieties exhibit similar increases in fiber length during development. . An analysis of fiber initiation (Figure 2) indicates that several different cotton varieties exhibit similar increases in fiber number per ovule over time. Previous literature indicates that during fiber development there are changes in the levels of the hormones Gibberellic Acid (GA) and indole acetic acid (IAA) Homework Assignment Generate 3 different hypotheses that you could test regarding the possible use of GA and IAA during fiber development to improve either cotton yield or quality. For each hypothesis generate a prediction.

Explanation / Answer

Hypotheses:
i. Since Auxin is involved in cell division, increased application of auxin on plants should increase the fiber length. This can be achieved either by generating an overexpression line for IAA biosynthetic gene or exogenous Auxin spraying.
ii. Since GA is involved in cell elongation, increased application of GA on plants should increase the fiber length.
iii. Increased application of both GA and Auxin should exhibit a cumulative effect as both hormones work synergistically.

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